I run over the counter motorcrafts. My other question is I hear talk about heat range or whatever. For instance a guy might say, "I run x plugs one range cooler." What is the benefit of this, when is it needed, and how do you know what the heat range is on the plugs you're buying? Oh and when I car is n/a the oem recommended gap is where you want to be or is that depended on mods etc?